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Biomedical subjects

M Castegnaro

Publications and source records attributed to M Castegnaro.

At least 109 records · Page 6Linked to original sources
PubMed1980

International mycotoxin check sample program. Part I. Report on the performance of participating laboratories.

Three aflatoxin-contaminated samples, raw peanut meal, finished peanut butter, and white corn meal, were analyzed by 139 laboratories in 34 countries. Sufficient data were obtained to permit a statistical comparison of the performance of laboratories using the BF, CB, and Pons methods and those using high performance liquid chromatography for quantification. A raw peanut meal sample showed no significant differences among means for laboratories using the four methods, and a white corn meal sample showed only one such significant difference; however, a finished peanut butter sample containing less than 10 micrograms total aflatoxins/kg showed 10 significant differences among means for laboratories using the 4 methods considered.

Aflatoxins↗
PubMed1979

Intake of volatile nitrosamines from consumption of alcohols.

Volatile nitrosamines were determined in alcoholic drinks during epidemiologic studies on the relationship between esophageal cancer incidence and alcohol consumption in Normandy, France. Nitrosodimethylamine (NDMA) was found commonly in most alcoholic drinks tested, with the exception of wine. The average level, about 2 micrograms/liter in beers, was higher than that for other drinks; the range was 0.2--8.6 micrograms/liter. Traces of nitrosodiethylamine (NDEA) were also detected in spirits and ciders. No significant increases in levels were found after nitrosation. Calculation of daily intake in the study region showed that the main intake of volatile nitrosamine is from NDMA in beer. The intake of NDEA through consumption of cider is about one-third that of NDMA from all sources.

Alcoholic Beverages↗
PubMed1978

Ingested mutagens from opium and tobacco pyrolysis products and cancer of the oesophagus.

Substances which are commonly sucked or chewed in two areas where the incidence of oesophageal cancer is high, the Transkei and north-east Iran, were tested in bacterial mutagenicity assays. Pyrolysed substances, opium dross in north-east Iran and tobacco pipe residues in the Transkei, displayed mutagenic activity in Salmonella typhimurium strains TA98 and TA100 in the presence of rat liver microsomes.

Administration, Oral↗
PubMed1976

Effects of gallic acid and of ethanol on formation of nitrosodiethylamine.

In vitro experiments demonstrate that the polyphenol, gallic acid, can both catalyse and inhibit NDEA formation. The products of reaction depend considerably on pH conditions and relative concentrations of the reactants. Therefore, interpretation of in vitro experiments in terms of possible in vivo effects in a given population must take into consideration detailed information on eating and drinking habits which might affect pH conditions and relative concentrations of the reactants in the digestive tract. In this respect, it is interesting to note that epidemiological studies conducted by the agency (Day 1) indicate that tea, which contains gallotannins, is consumed more frequently but in a more diluted brew in the area of high oesophageal cancer incidence of the Caspian littoral than in the low incidence area. Our preliminary study on ethanol suggests that its effects will be found to lack the complications present with the tannins and would thus be more easily extrapolated to in vivo situations.

Catalysis↗
PubMedDate not supplied

Carcinogen metabolism and DNA adducts in human lung tissues as affected by tobacco smoking or metabolic phenotype: a case-control study on lung cancer patients.

Individual variations in activity of pulmonary enzymes that metabolize tobacco-derived carcinogens may affect an individual's cancer risk from cigarette smoking. To investigate whether some of these enzymes (e.g., cytochrome P450IA-related) can serve as markers for carcinogen-induced DNA damage accumulating in the lungs of smokers, non-tumorous lung tissue specimens were taken during surgery from middle-aged men with either lung cancer (n = 54) or non-neoplastic lung disease (n = 20). Phase I (AHH, ECDE) and phase II (EH, UDPGT, GST) enzyme activities, glutathione and malondialdehyde contents were determined in lung parenchyma and/or bronchial tissues; some samples were analyzed for DNA adducts, using 32P-postlabeling. Data analysis of subsets or the whole group of patients yielded the following results. (1) Phase I and II drug-metabolizing enzyme (AHH, EH, UDPGT, GST) activities in histologically normal surgical specimens of lung parenchyma were correlated with the respective enzyme activities in bronchial tissues of the same subject. (2) In lung parenchyma, enzyme (AHH, ECDE, EH, UDPGT) activities were significantly and positively related to each other, implying a similar regulatory control of their expression. (3) Mean activities of pulmonary enzymes (AHH, ECDE) were significantly (2- and 7-fold, respectively) higher in lung cancer patients who had smoked within 30 days before surgery (except GST, which was depressed) than in cancer-free subjects with a similar smoking history. (4) In the cancer patients, the time required for AHH, EH and UDPGT activities to return to the level found in non-smoking subjects was several weeks. (5) Bronchial tree and peripheral lung parenchyma preparations exhibited a poor efficiency in activating promutagens to bacterial mutagens in Salmonella. However, they decreased the mutagenicity of several direct-acting mutagens, an effect which was more pronounced in tissue from recent smokers. GSH concentration and GST activity were positively correlated with mutagen inactivation in the same sample. (6) In recent smokers, AHH activity in lung parenchyma was positively correlated with the level of tobacco smoke-derived DNA adducts. (7) Pulmonary AHH and EH activity had prognostic value in tobacco-related lung cancer patients. (8) An enhanced level of pro-oxidant state in the lungs was associated with recent cigarette smoking. Malondialdehyde level in lung parenchyma was associated with the degree of small airway obstruction, suggesting a common free radical-mediated pathway for both lung cancer induction and small airway obstruction.(ABSTRACT TRUNCATED AT 250 WORDS)

Adult↗
PubMedDate not supplied

Ochratoxin A contamination of cereals in an area of high incidence of Balkan endemic nephropathy in Bulgaria.

In an effort to provide further evidence for the hypothesis that a mycotoxin is involved in the aetiology of Balkan endemic nephropathy and that the latter is associated with the occurrence of urinary system tumours, a survey was made of ochratoxin A contamination of cereal samples from an area of Bulgaria where both endemic nephropathy and urinary system tumours are prevalent and from non-endemic areas. In all, 130 samples of beans, maize and wheat flour were analysed. Ochratoxin A levels were 16.7% (25-27 micrograms/kg) in bean samples from the endemic area and 7.1% (25-50 micrograms/kg) in those from the control areas: in maize samples, the levels were 27.3% (25-35 micrograms/kg) and 9.0% (10-25 micrograms/kg), respectively.

Balkan Nephropathy↗
PubMedDate not supplied

The collaborative evaluation of a procedure for the determination of N-nitroso compounds as a group.

Two collaborative studies have been made of the method devized for the determination of N-nitroso compounds as a group, which involves their selective denitrosation with hydrogen bromide in glacial acetic acid, followed by the measurement of the nitric oxide liberated using a chemiluminescence analyzer, such as the TEA. Considerable variation was evident between the results in the first study, most of the values reported being low. This situation undoubtedly arose from the carry-over of traces of hydrogen bromide from one determination to the next, which resulted in premature denitrosation. The precision and consistency of the results were greatly improved in the second study, for which additional precautions had been recommended. All of the six participating laboratories reported reasonably consistent values, the coefficients of variation being 27.9% and 21.1% respectively, at the levels of spiking of N-nitrososarcosine equivalent to 32.9 ng and 146.4 ng of nitric oxide.

Indicators and Reagents↗
PubMedDate not supplied

International N-nitrosamine check sample programme: report on the performance in the 1st study dedicated to determination of N-nitrosamines in beer and malt.

Two samples, one beer and one malt, have been distributed to 55 laboratories in 15 countries, to be analysed for N-nitrosodimethylamine (NDMA) N-nitrosopyrollidine (NPYR) and N-nitrosoproline (NPRO) by the method of their choice. Results received from 35 laboratories demonstrated that at the low levels of contamination which may be encountered at present for NDMA in beer and malt, generally reliable data can be obtained in malt, but in beer, 20% of the results were discarded as outliers by the statistical test results. More variability was encountered for the analysis of NPYR. Only a limited number of results were provided for NPRO, which also showed greater variability.

Alcoholic Beverages↗
PubMedDate not supplied

Ochratoxin A in human blood in relation to Balkan endemic nephropathy and urinary system tumours in Bulgaria.

In continuing the effort to provide further evidence for the hypothesis that ochratoxin A might be involved in the aetiology of Balkan endemic nephropathy and the associated urinary system tumours, a survey to determine the occurrence of ochratoxin A in human blood was conducted in affected and unaffected areas of Bulgaria, where both diseases are prevalent. Ochratoxin A, positive samples, were present more often in blood from affected patients and the contamination levels were generally higher.

Balkan Nephropathy↗